Background: Pulmonary arterial hypertension (PAH) is a progressive disease characterized by elevated pressure in the pulmonary arteries, commonly resulting in right heart failure. PAH is associated with a high economic burden throughout the duration of the disease., Methods: This retrospective cohort study of the Milliman Contributor Health Source Data, the Medicare 100% Research Identifiable Files, and the Merative Marketscan ® Commercial dataset between 2018 and 2020 identified adult patients with prevalent PAH based on the earliest qualifying diagnosis date or medication date ('index date') between January 1, 2019 and November 30, 2020. Outcomes were assessed using patient data from index date through the earliest of end of enrollment, end of data, or death (Medicare fee-for-service [FFS] only). All-cause and PAH-related medical and pharmacy costs per-patient per-month (PPPM) and healthcare resource utilization per 1000 patients were summarized., Results: The study included 11,670 Medicare FFS, 1021 Medicare Advantage, 274 Medicaid, and 1174 commercially insured patients in the US. The annual national burden to payers was estimated to be US$3.1 billion. The PPPM payer costs ranged from US$6500 to US$14,742; out-of-pocket (OOP) costs ranged from US$341 to US$907 PPPM. Inpatient utilization rate ranged from 435 to 770 per 1000 patients for all-cause admissions and from 15 to 58 per 1000 patients for PAH-related admissions., Conclusions: This study demonstrates that PAH continues to be associated with a high economic burden and healthcare resource utilization across all payer types within the US healthcare system., Competing Interests: Declarations. Funding: This research was funded by Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc., Rahway, NJ, USA. Conflict of interest: AW, DL, and AA are employees of Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc., Rahway, NJ, USA at time of manuscript submission. CF, GD, and CP are employees of Milliman, Inc., who received consulting fees from Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc., Rahway, NJ, USA. KEK participated in United Therapeutics speaker’s bureau 2018–2021 and served on advisory boards and as a consultant for United Therapeutics, J&J Actelion, Acceleron, and Merck & Co., Inc., Rahway, NJ, USA. Ethics approval: Ethics approval is not required as this project does not include any interaction with human subjects and only uses publicly available de-identified claims data. Informed consent: Not applicable. Availability of data and materials: The data that support the findings of this study are available from the authors but restrictions apply to the availability of these data, which were obtained under license from the Centers for Medicare & Medicaid Services (CMS), Merative L.P., and Milliman, Inc.. As such, data used for this study are not publicly available. Author contributions: Substantial contributions to the conception or design of the work: all authors. Data analysis: CF, CP. Interpretation of data for the work: all authors. Drafting the work or reviewing it critically for important intellectual content: all authors. Final approval of the version to be published: all authors. The authors agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved., (© 2024. Merck & Co., Inc., Rahway, NJ, USA and its affiliates, and Milliman, Inc., New York, NY, USA.)